JP2009237413A - Calibration- method of spatial light modulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the value of light quantity parameter constant at a part corresponding to an ON-element group in an light quantity distribution, obtained by alternately setting the ON-element groups and OFF-element groups on a light modulation element line. <P>SOLUTION: An initial light quantity distribution is obtained by setting all the light modulating elements 461 in the ON-state. Next, the values of the light quantity parameter expressing the width W1 of at least a predetermined light quantity are obtained for the ON-light quantity parts 71, corresponding to the respective ON-element groups 462 in the light quantity distribution obtained by alternately setting the ON-element groups 462 and an OFF-element groups 463, and the variation tendency curve is obtained that shows the variation tendency in the direction, corresponding to the arranged direction of the values of the light quantity parameter. A target light quantity distribution is produced, of which the value becomes smaller as the value becomes larger, with the value being obtained by dividing the values of variation tendency curve at positions, corresponding to the respective optical modulation elements 461 by the values of the initial light quantity distribution at the positions, and the input values to the respective light modulating elements 461 are corrected so that the light quantity distribution approximates the target light quantity distribution, while all the light modulating elements 461 are set to ON-state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spatial light modulator having a light modulation element array in which a large number of light modulation elements are arranged in a predetermined arrangement direction, by correcting the input value to each light modulation element in the light modulation element array. The present invention relates to a calibration method for a spatial light modulator that corrects the distribution of the amount of light output from the detector.

  A diffraction grating capable of changing the depth of a diffraction grating by alternately forming fixed ribbons and flexible ribbons on a substrate using semiconductor device manufacturing technology and bending the flexible ribbons relative to the fixed ribbons. Types of light modulation elements have been developed. In such a diffraction grating, the intensity of specularly reflected light and diffracted light changes by changing the groove depth, so that it is proposed to be used for an image recording apparatus that records an image on various recording media as a light switching element. ing.

  For example, a light modulation element array in which a large number of light modulation elements are arranged in the arrangement direction is provided in the image recording apparatus, and the light modulation element array is irradiated with light so that the fixed ribbon and the flexible ribbon are at the same height from the reference plane. Reflected light (0th order light) from the light modulation element (ribbon pair) in a positioned state is guided to the recording medium, and non-zero order diffracted light (mainly first order diffracted light) from the light modulation element in a state where the flexible ribbon is bent. ) Is light-shielded, image recording onto a recording medium is realized (see, for example, Patent Documents 1 and 2 as such an image recording apparatus).

  By the way, in the diffraction grating type light modulation element array, even if a constant drive voltage is input to a plurality of light modulation elements, the characteristics of each light modulation element (physical properties of the flexible ribbon) may vary due to variations in the light modulation element manufacturing. Behavioral characteristics and electrical characteristics) vary. Therefore, in an image recording apparatus having a large number of light modulation elements, an operation (calibration) is performed to adjust the amount of light emitted from the light modulation element array onto the recording medium. In the calibration, first, all the light modulation elements are turned on to guide light onto the recording medium, and light is received from the light modulation elements at a light receiving portion arranged at a position equivalent to the recording medium, thereby arranging the light modulation elements. A light amount distribution in a direction corresponding to the direction is acquired. Then, by adjusting the drive voltage to the light modulation element in accordance with the light quantity value corresponding to each light modulation element, a drive voltage having a constant light quantity value is obtained for every light modulation element. Is done. In the calibration, the influence of non-uniformity of the intensity of the illumination light irradiated on the light modulation element array and the aberration of the projection optical system that guides the light from the light modulation element array to the recording medium are substantially corrected. It will be.

In Patent Document 3, the minimum drawing line width on the photosensitive material is made to correspond to the width of two or more ribbon pairs on the diffraction grating type spatial light modulator, and always more than the predetermined number at the time of drawing. The ribbon pair is continuously diffracted, and a predetermined number or more of ribbon pairs are continuously reflected so that the width on the photosensitive material corresponding to the width of the ribbon pair is set as an address resolution on the photosensitive material. A method for recording the above has been proposed.
JP 2004-4525 A JP 2007-121998 A JP 2007-121881 A

  However, as described above, even when calibration is performed with all the light modulation elements turned on, a predetermined number of light modulation elements continuous in the arrangement direction are turned on using the drive voltage obtained by the calibration. When the ON element group and the OFF element group in which the predetermined number of light modulation elements continuous in the arrangement direction are turned off are repeatedly set, the maximum light amount corresponding to all the ON element groups is not constant. In this case, the image cannot be recorded on the recording medium with high accuracy. In the image recording apparatus, the width of the portion corresponding to the ON element group in the light amount distribution when the ON element group and the OFF element group are repeatedly set in the arrangement direction (a width equal to or greater than the predetermined light amount) is important. In many cases, such a width cannot be directly used as an index in the calibration.

  The present invention has been made in view of the above-described problems, and it is possible to easily perform calibration by setting all the light modulation elements in the light modulation element array to the ON state, and to connect the ON element group and the OFF element group in the light modulation element array. The purpose is to make the values of the light quantity parameters such as the maximum light quantity and the width of the part corresponding to the ON element group in the light quantity distribution when repeated in the arrangement direction constant.

  According to the first aspect of the present invention, in the spatial light modulator having a light modulation element array in which a large number of light modulation elements are arranged in a predetermined arrangement direction, an input value to each light modulation element of the light modulation element array is corrected. A method of calibrating the spatial light modulator for correcting the distribution of the output light quantity from the spatial light modulator by: a) irradiating light to all the light modulation elements of the light modulation element array The light receiving unit disposed on the projection surface receives light from the light modulation element array in an ON state guided to the projection surface, and in a direction corresponding to the arrangement direction on the projection surface. A step of obtaining a first light quantity distribution; b) an ON element group in which a predetermined number of light modulation elements continuous in the arrangement direction are turned on using input values to the light modulation elements in the step a) , A predetermined number of lights continuous in the arrangement direction The light receiving unit receives light from the light modulation element array while repeatedly setting the OFF element group in which the adjusting elements are in the OFF state in the arrangement direction, and corresponds to the arrangement direction on the projection plane. A step of obtaining a second light quantity distribution in the direction; c) a width corresponding to each ON element group in the second light quantity distribution, a maximum light quantity or a cumulative light quantity obtained by integrating the light quantity with the width. Obtaining a light quantity parameter value to be obtained, and obtaining a fluctuation tendency curve indicating a fluctuation tendency in a direction corresponding to the arrangement direction of the light quantity parameter values in all ON element groups; and d) corresponding to each of the light modulation elements. The first light quantity distribution is modified so that the larger the value obtained by dividing the value of the fluctuation tendency curve at the position on the projection plane by the value of the first light quantity distribution at the position, the smaller the value. E) creating a target light amount distribution, and e) turning on all the light modulation elements of the light modulation element array so that the light amount distribution acquired by the light receiving unit approximates the target light amount distribution. And a step of correcting an input value to each of the light modulation elements.

  A second aspect of the present invention is the spatial light modulator calibration method according to the first aspect, wherein the first light quantity distribution is a constant value in the step a).

  A third aspect of the present invention is the calibration method of the spatial light modulator according to the first or second aspect, wherein the object crosses a direction corresponding to the arrangement direction on the projection plane. An image is recorded on the object by moving relative to the spatial light modulator, and the number of light modulation elements in the ON element group and the number of light modulation elements in the OFF element group are The number is greater than or equal to the minimum line width that can be drawn on the object.

  The invention described in claim 4 is the calibration method of the spatial light modulator according to any one of claims 1 to 3, wherein the step c) sets the value of the light quantity parameter in all the ON element groups. After obtaining, there is a step of reducing the fluctuation of the value.

  A fifth aspect of the present invention is the spatial light modulator calibration method according to any one of the first to fourth aspects, wherein the light modulation element array includes a band-shaped fixed reflection surface, a flexible reflection surface, and the like. Are diffraction grating type light modulation element arrays arranged alternately.

  According to the present invention, the amount of light in the case of repeating the ON element group and the OFF element group in the arrangement direction in the light modulation element array while easily performing calibration with all the light modulation elements in the light modulation element array being in the ON state. The value of the light quantity parameter of the portion corresponding to the ON element group in the distribution can be made constant.

  In the invention of claim 2, the value of the light quantity parameter can be made constant with high accuracy. In the invention of claim 5, the dispersion of the light quantity parameter value depending on the diffraction grating type spatial light modulator can be easily performed. Can be suppressed.

  FIG. 1 is a side view of the image recording apparatus 1 according to the first embodiment of the present invention, and FIG. 2 is a plan view of the image recording apparatus 1. The image recording device 1 is a device that records an image (draws a pattern) by irradiating light onto a photosensitive material on a glass substrate (hereinafter simply referred to as “substrate”) for a liquid crystal display device. As shown in FIGS. 1 and 2, the image recording apparatus 1 is a substrate that holds a substrate 9 on which a layer of a photosensitive material is formed on a main surface 91 (hereinafter referred to as “upper surface 91”) on the (+ Z) side. The holding unit 3 is provided on the base 11 so as to straddle the holding unit moving mechanism 2 that moves the substrate holding unit 3 in the X direction and the Y direction perpendicular to the Z direction, and the substrate holding unit 3 and the holding unit moving mechanism 2. A frame 12 that is fixed to the base 11 and a light irradiation unit 4 that is attached to the frame 12 and that emits modulated light to the photosensitive material on the substrate 9 are provided. Further, as shown in FIG. 1, the image recording apparatus 1 includes a control unit 6 that controls each configuration of the holding unit moving mechanism 2, the light irradiation unit 4, and the like, and the control unit 6 transmits light from the light irradiation unit 4. It has a modulator control unit 61 that performs emission control, and a calculation unit 62 that performs a predetermined calculation during processing related to calibration described later.

  The substrate holding unit 3 has a stage 31 on which the substrate 9 is placed, a support plate 33 that rotatably supports the stage 31, and a rotation axis 321 perpendicular to the upper surface 91 of the substrate 9 on the support plate 33. A stage rotation mechanism 32 that rotates the stage 31 is provided. In addition, a light receiving unit 34 having a slit and a photodiode is disposed on the (−Y) side end of the stage 31 so as not to overlap the substrate 9 on the stage 31, and the light receiving surface of the light receiving unit 34 in the Z direction. Is substantially the same height as the upper surface 91 of the substrate 9.

  The holding unit moving mechanism 2 includes a sub-scanning mechanism 23 that moves the substrate holding unit 3 in the X direction in FIGS. 1 and 2 (hereinafter referred to as “sub-scanning direction”), and a support plate 33 via the sub-scanning mechanism 23. And a main scanning mechanism 25 that moves the substrate holder 3 together with the base plate 24 in the Y direction perpendicular to the X direction (hereinafter referred to as “main scanning direction”). In the image recording apparatus 1, the holding unit moving mechanism 2 moves the substrate holding unit 3 in the main scanning direction and the sub-scanning direction parallel to the upper surface 91 of the substrate 9.

  As shown in FIGS. 1 and 2, the sub-scanning mechanism 23 is arranged on the lower side of the support plate 33 (that is, on the (−Z) side) parallel to the main surface of the stage 31 and perpendicular to the main scanning direction. A linear motor 231 extending in the scanning direction and a pair of linear guides 232 extending in the sub-scanning direction on the (+ Y) side and the (−Y) side of the linear motor 231 are provided. The main scanning mechanism 25 has a linear motor 251 extending in a main scanning direction parallel to the main surface of the stage 31 below the base plate 24, and a main scanning direction on the (+ X) side and the (−X) side of the linear motor 251. A pair of air sliders 252 extending in the direction.

  As shown in FIG. 2, the light irradiation unit 4 includes a plurality (four in the present embodiment) of optical heads 41 arranged at an equal pitch along the sub-scanning direction and attached to the frame 12. As shown in FIG. 1, the light irradiation unit 4 includes a light source optical system 42 connected to each optical head 41, a UV light source 43 that emits ultraviolet light, and a light source driving unit 44. The UV light source 43 is a solid-state laser, and when the light source driving unit 44 is driven, ultraviolet light is emitted from the UV light source 43 and guided to the optical head 41 via the light source optical system 42.

  Each of the optical heads 41 emits light from the UV light source 43 downward, an optical unit 451 that reflects the light from the output unit 45 and guides it to the spatial light modulator 46, and the optical system 451. The spatial light modulator 46 that reflects and modulates the light emitted from the emitting portion 45, and the modulated light from the spatial light modulator 46 onto the photosensitive material provided on the upper surface 91 of the substrate 9. A guiding optical system 47 is provided.

  FIG. 3 is an enlarged view of the spatial light modulator 46. As shown in FIG. 3, the spatial light modulator 46 has a diffraction grating type light modulation element array 460, and the light from the UV light source 43 irradiated through the emitting unit 45 is transmitted by the light modulation element array 460. Guided to the upper surface 91 of the substrate 9. The light modulation element array 460 is manufactured using a semiconductor device manufacturing technique, and is a diffraction grating capable of changing the depth of the grating. In the light modulation element array 460, a plurality of flexible ribbons 461a and fixed ribbons 461b are alternately arranged in parallel. The plurality of flexible ribbons 461a can be individually moved up and down with respect to a reference plane behind the plurality of flexible ribbons 461a. The fixed ribbon 461b is fixed with respect to the reference plane. In the following description, the direction in which the plurality of flexible ribbons 461a and the fixed ribbon 461b are arranged is referred to as an arrangement direction.

  In the light modulation element array 460, each ribbon pair (which may be a set of a plurality of ribbon pairs) can be individually controlled by using each one adjacent flexible ribbon 461 a and fixed ribbon 461 b as one ribbon pair. The drive circuit 611 of the modulator control unit 61 is connected to each of a large number (for example, 100 or more) of light modulation elements 461 arranged in the arrangement direction. By changing the drive voltage input to the drive circuit 611, the height (deflection amount) of the flexible ribbon 461a with respect to the reference surface can be changed. That is, the drive voltage is an input value that commands the height of the flexible ribbon 461 a in each light modulation element 461. For example, GLV (Grating Light Valve) (registered trademark of Silicon Light Machines (Sunnyvale, Calif.)) Is known as a diffraction grating type light modulation element array.

  FIG. A and FIG. B is a view showing a cross section of the light modulation element array 460 in a plane perpendicular to the flexible ribbon 461a and the fixed ribbon 461b. FIG. As shown in A, when the flexible ribbon 461a and the fixed ribbon 461b are positioned at the same height with respect to the reference surface 461c, the surface of the light modulation element array 460 is flush and the reflected light of the incident light L1 is 0. Derived as the next light L2. On the other hand, FIG. When the flexible ribbon 461a is positioned closer to the reference surface 461c than the fixed ribbon 461b (bends) as shown in B, the flexible ribbon 461a becomes the bottom surface of the groove of the diffraction grating, and the first-order diffracted light L3 (and further , Higher-order diffracted light) is derived from the light modulation element array 460, and the zero-order light L2 disappears. As described above, the light modulation element array 460 performs light modulation using a diffraction grating.

  In the light irradiation unit 4 shown in FIG. 1, the light from the UV light source 43 is converted into linear light (light having a light beam cross-section linear) by the light source optical system 42, and the line of the spatial light modulator 46 is passed through the emission unit 45. Irradiation is performed on a plurality of flexible ribbons 461a and fixed ribbons 461b (see FIG. 4.A and FIG. 4.B) arranged in a shape.

  In the light modulation element 461, when a predetermined ON drive voltage is input to each drive circuit 611, a corresponding ribbon pair emits 0th-order light (regular reflection light), and a predetermined OFF drive voltage is input. Accordingly, the corresponding ribbon pair emits non-zero order diffracted light (mainly first order diffracted light ((+1) order diffracted light and (−1) order diffracted light)). The 0th-order light emitted from the light modulation element 461 is guided to the optical system 47, and the first-order diffracted light is guided in a direction different from that of the optical system 47. In order to prevent stray light from being generated, the first-order diffracted light is shielded by a light shielding unit (not shown).

  The zero-order light from the light modulation element 461 is guided to the upper surface 91 of the substrate 9 through the optical system 47, and thereby a plurality of irradiation positions arranged in the X direction (sub-scanning direction) on the upper surface 91 of the substrate 9. Each of these is irradiated with modulated light. That is, in the ribbon pair corresponding to each pixel of the light modulation element 461, the reflection state for emitting the 0th order light is turned on, and the diffraction state for emitting the first order diffracted light is turned off. In the image recording apparatus 1 according to the present embodiment, the wavelength of light from the UV light source 43 is 355 nanometers (nm), the pitch in the arrangement direction of the light modulation elements 461 is 7 micrometers (μm), and the spatial light of the optical system 47 The NA (numerical aperture) on the modulator 46 side is set to 0.01, and the minimum width of an object that can be resolved on the substrate 9 by the optical system 47 is set to 35 μm corresponding to five light modulation elements 461. In the following description, a plane including the upper surface 91 of the substrate 9 on which an image of the light modulation element array 460 is formed by the optical system 47 is referred to as a projection plane.

  In the image recording apparatus 1 shown in FIGS. 1 and 2, the light modulated from the light modulation element 461 of the light irradiation unit 4 is applied to the substrate 9 moved in the main scanning direction by the main scanning mechanism 25 of the holding unit moving mechanism 2. Is irradiated. In other words, the main scanning mechanism 25 moves the irradiation position on the substrate 9 of the light guided from the light modulation element 461 to the substrate 9 relative to the substrate 9 in the main scanning direction. It has become. In the image recording apparatus 1, the modulator control unit 61 of the control unit 6 controls the modulation of the light from the light modulation element 461 based on the drawing data prepared in advance, so that the pattern indicated by the drawing data is changed to the substrate 9. Rendered on top. At this time, in the image recording apparatus 1, the distribution of the light amount (hereinafter referred to as “output light amount”) irradiated from the spatial light modulator 46 onto the substrate 9 is highly accurate pattern drawing by calibration described later. Has been adjusted to a possible state.

  Actually, in the image recording apparatus 1, as in the technique of the above-mentioned Japanese Patent Application Laid-Open No. 2007-121881 (Patent Document 3), the light modulation element 461 is individually switched between the ON state and the OFF state. At the time of drawing, a predetermined number (5 in this embodiment) or more of the light modulation elements 461 are continuously turned on in the arrangement direction, and a predetermined number or more of the light modulation elements 461 are continuously turned off in the arrangement direction. Control is performed so that an image is recorded on the substrate 9 with high position resolution.

  Next, processing related to calibration for correcting the distribution of the output light amount from the spatial light modulator 46 in the image recording apparatus 1 will be described with reference to FIG. Note that the calibration is a process that is periodically performed when the image recording apparatus 1 is used, for example. Hereinafter, the description will be made by paying attention to the spatial light modulator 46 of one optical head 41 among the plurality of optical heads 41, but the same processing is performed for the spatial light modulators 46 of other optical heads 41. Is called.

  In the process related to the calibration of the spatial light modulator 46, first, the light receiving unit 34 on the stage 31 is arranged at the same position as the plurality of optical heads 41 in the Y direction by the main scanning mechanism 25 in FIG. At this time, the light receiving unit 34 is disposed, for example, on the (−X) side of the optical head 41. Subsequently, in the spatial light modulator 46 of the optical head 41, a constant drive voltage (hereinafter referred to as "initial drive voltage") is input to the drive circuits 611 of all the light modulation elements 461, whereby all the light modulations are performed. The element 461 is turned on, and the light applied to the light modulation element array 460 is guided to the projection surface. Then, when the stage 31 is continuously moved in the (+ X) direction by the sub-scanning mechanism 23, the light from the light modulation element array 460 is received by the light receiving unit 34 disposed on the projection surface. Thereby, a measurement value of the light amount of the light (that is, the amount of light irradiated to the unit area per unit time) is acquired and output to the calculation unit 62, and the light amount distribution in the X direction on the projection plane is acquired. (Step S11). Hereinafter, the state of the light modulation element array 460 that turns on all the light modulation elements 461 is referred to as an all-ON lighting pattern.

  In the calculation unit 62, the position in the X direction in the light amount distribution of the all-ON lighting pattern (that is, the position in the X direction corresponding to the light modulation element 461) is specified according to the position in the arrangement direction of each light modulation element 461. The amount of light at the position (which may be an average value within a predetermined range centered on the position, etc.) is specified as the measured value of the light modulation element 461. Subsequently, an upper limit value obtained by adding a predetermined value to a predetermined set value and a lower limit value obtained by subtracting the predetermined value from the set value are obtained. The upper limit value and the lower limit value may be obtained in advance. The set value may be an average value or a minimum value of all measured values in the light amount distribution of the all-ON lighting pattern.

  When the upper limit value and the lower limit value are obtained, the light modulation element 461 corresponding to the measurement value larger than the upper limit value is set according to the difference between the measurement value and the set value so that the light amount is smaller than the measurement value. Thus, the value of the initial drive voltage is changed (updated), and the measured value and the set value are set so that the amount of light is larger than the measured value with respect to the light modulation element 461 corresponding to the measured value smaller than the lower limit value. The value of the initial drive voltage is changed according to the difference. Further, the initial drive voltage is not changed for the light modulation element 461 corresponding to the measurement value that is equal to or lower than the upper limit value and equal to or higher than the lower limit value (step S12).

  Subsequently, by inputting the initial drive voltage (after the change) to the drive circuits 611 of all the light modulation elements 461, all the light modulation elements 461 are turned on, and the light amount distribution of all ON lighting patterns is acquired. (Steps S13 and S11) In the same manner as described above, the light modulation element 461 corresponding to the measurement value larger than the upper limit value and the light modulation element 461 corresponding to the measurement value smaller than the lower limit value are The value of the initial drive voltage is changed according to the difference between the measured value and the set value, and the value of the initial drive voltage is changed for the light modulation element 461 corresponding to the measured value that is less than or equal to the upper limit value and greater than or equal to the lower limit value. Is not performed (step S12).

  In the calculation unit 62, the processes in steps S11 and S12 are repeated until the measured values corresponding to all the light modulation elements 461 are equal to or lower than the upper limit value and equal to or higher than the lower limit value (step S13). As shown in FIG. 5, the light amount distribution of the all-ON lighting pattern in which the measured values for all the light modulation elements 461 are substantially constant at the set value E1 is obtained. In the following description, the light amount distribution of all ON lighting patterns when the measurement values corresponding to all the light modulation elements 461 are equal to or lower than the upper limit value and equal to or higher than the lower limit value is referred to as a corrected initial light amount distribution. The initial driving voltage when the distribution is acquired is referred to as a final initial driving voltage.

  Subsequently, a predetermined number of ON-state light modulation elements 461 (hereinafter referred to as “ON element group”) continuous in the arrangement direction and a predetermined number of OFF-state light modulation elements 461 (hereinafter referred to as “hereinafter“ ON element group ”) in the arrangement direction. "OFF element group") is repeatedly set in the arrangement direction. At this time, the final initial drive voltage when the corrected initial light quantity distribution is acquired is input to the drive circuit 611 of each light modulation element 461 of the ON element group. In the light modulation element array 460, an OFF drive voltage that minimizes the light amount (0th order light) is acquired in advance for each light modulation element 461, and is supplied to the drive circuit 611 of each light modulation element 461 in the OFF element group. Is inputted with the OFF drive voltage.

  Then, the light receiving unit 34 continuously moves in the X direction on the projection surface, and the light receiving unit 34 receives the light from the light modulation element array 460, thereby obtaining the light amount distribution in the X direction on the projection surface. (Step S14). In the present embodiment, the number of light modulation elements 461 in each ON element group is five, and the number of light modulation elements 461 in each OFF element group is also five. Hereinafter, the state of the light modulation element array 460 in which the ON element group and the OFF element group are repeatedly set in the arrangement direction is referred to as an ON / OFF lighting pattern. The light quantity distribution acquired in the ON / OFF lighting pattern is the diffracted light (each light from the light modulation element array 460 when the ON element group and the OFF element group of the light modulation element array 460 are regarded as elements of the diffraction grating. This is different from the first-order diffracted light from the modulation element 461, and the width of the element of the diffraction grating substantially coincides with the pupil diameter of the optical system 47 (the lens thereof).

  FIG. 7 is a diagram showing a part of the light amount distribution in the ON / OFF lighting pattern. In the lower part of FIG. 7, the vertical axis indicates the light amount, the horizontal axis indicates the position in the X direction, and the upper part of FIG. A and FIG. A cross section of the light modulation element array 460 is shown corresponding to B.

  As shown in the lower part of FIG. 7, in the light quantity distribution of the ON / OFF lighting pattern, the light quantity corresponds to the ON element group (indicated by reference numeral 462 in the upper part of FIG. 7) that is turned on using the initial drive voltage. A large mountain-shaped portion (a portion indicated by reference numeral 71 in the lower part of FIG. 7 and hereinafter referred to as “ON light quantity part”) and an OFF element group (reference numeral 463 in the upper part of FIG. 7). There is a valley-like portion with a small amount of light corresponding to, and the calculation unit 62 obtains the maximum light amount in the entire light amount distribution of the ON / OFF lighting pattern. For example, the value of 30% of the maximum light amount is a light amount. It is obtained as the threshold value T1. The light amount threshold T1 is determined in accordance with the amount of light that the photosensitive material on the substrate 9 is exposed to light (denatured by a cross-linking reaction). In this embodiment in which the photosensitive material is a photoresist, the maximum light amount is 10. The value is set to ˜40%. Note that the light amount distribution shown in the lower part of FIG. 7 can also be regarded as a profile of an optical image showing the light modulation element array 460 of the ON / OFF lighting pattern.

  Subsequently, the width W1 of the portion that is equal to or greater than the light amount threshold value T1 in each ON light amount portion 71 is obtained as a light amount parameter, and the position of the ON light amount portion 71 in the X direction (for example, the center of the ON light amount portion 71 in the X direction range). ) Is associated with the value of the light quantity parameter (width W1). In the calculation unit 62, an average value of the light quantity parameter value is obtained for each predetermined number (for example, 3 to 10) of the ON light quantity portions 71, and the light quantity parameter value for each ON light quantity portion 71 is set to the average value. Be changed. In this way, after obtaining the light quantity parameter values in all the ON element groups 462, fluctuations in the values are reduced by calculation, and noise components in the light quantity measurement values are removed (step S15).

  Then, in the two-dimensional region defined by the X direction and the light quantity parameter, a point indicating the value of the light quantity parameter corresponding to the ON light quantity portion 71 is plotted at the position in the X direction of each ON light quantity portion 71 and adjacent 2 By interpolating between the two points by a predetermined method, a fluctuation tendency curve indicating the fluctuation tendency in the X direction of the light quantity parameter values in all the ON element groups 462 is acquired as shown in FIG. S16). In addition, the vertical axis | shaft of FIG. 8 shows the light quantity parameter (width W1), and a horizontal axis shows the position of a X direction.

  In the calculation unit 62, the average value V1 of the light amount parameter in the entire fluctuation tendency curve is obtained, and the value of the light amount parameter is normalized by dividing the value of the light amount parameter at each position in the X direction by the average value V1, For the position in the X direction corresponding to each light modulation element 461, a value obtained by subtracting 1 from the normalized value (that is, the difference between the light quantity parameter value at each position and the average value V1 is the average value V1). Divided value) is obtained as an evaluation value. Subsequently, each evaluation value is multiplied by (−1) to invert the positive and negative signs of the evaluation value, then multiplied by a predetermined coefficient (for example, 0.3 to 3), and 1 is added. As shown in FIG. 9, a correction coefficient is obtained for the position in the X direction corresponding to each light modulation element 461.

  Thereafter, in the corrected initial light quantity distribution shown in FIG. 6, the value of the position in the X direction corresponding to each light modulation element 461 is multiplied by the correction coefficient of the position. Thus, the corrected initial light amount distribution is corrected so that the value of the fluctuation tendency curve at the position on the projection surface corresponding to each light modulation element 461 becomes smaller, and the all-ON lighting pattern shown in FIG. A target light quantity distribution is created (step S17).

  When the target light quantity distribution is created, the final initial drive voltage is input to the drive circuits 611 of all the light modulation elements 461, so that all the light modulation elements 461 are turned on, and all the ON lighting patterns are displayed. A light amount distribution is acquired (step S18).

  In the calculation unit 62, an upper limit value obtained by adding a predetermined value to a target light amount distribution value (hereinafter referred to as “target value”) and a predetermined value for the position in the X direction corresponding to each light modulation element 461. The subtracted lower limit is set individually. In the light amount distribution of the all-ON lighting pattern obtained in step S18, the light amount is smaller than the measured value for the light modulation element 461 corresponding to the measured value larger than the upper limit value (at that position). Then, a value changed from the final initial drive voltage in accordance with the difference between the measured value and the target value (at that position) is acquired as a corrected drive voltage, and the light modulation element 461 corresponding to the measured value smaller than the lower limit value. On the other hand, a value changed from the final initial drive voltage in accordance with the difference between the measured value and the target value so that the amount of light is larger than the measured value is acquired as the corrected drive voltage. In addition, for the light modulation element 461 corresponding to the measurement value that is equal to or lower than the upper limit value and equal to or higher than the lower limit value, the final initial drive voltage is directly used as the corrected drive voltage (step S19). As will be described later, since the processing of steps S18 and S19 is repeated to change (update) the corrected drive voltage, step S19 in FIG. 5 shows the contents when the processing is repeated.

  Subsequently, by inputting a corrected drive voltage (after the change) to the drive circuits 611 of all the light modulation elements 461, all the light modulation elements 461 are turned on, and the light amount distribution of all ON lighting patterns is acquired. (Steps S20 and S18), similarly to the above, the measurement is performed on the light modulation element 461 corresponding to the measurement value larger than the upper limit value and the light modulation element 461 corresponding to the measurement value smaller than the lower limit value. The value of the corrected drive voltage is changed according to the difference between the value and the target value, and for the light modulation element 461 corresponding to the measured value that is equal to or lower than the upper limit value and equal to or higher than the lower limit value, the value of the corrected drive voltage is changed. Not performed (step S19).

  In the calculation unit 62, when the processes in steps S18 and S19 are repeated and the measured values for all the light modulation elements 461 are equal to or lower than the upper limit value (at the position) and equal to or higher than the lower limit value, the final corrected drive voltage is determined. (That is, the corrected drive voltage when acquiring the light amount distribution of all ON lighting patterns in which the measured values for all the light modulation elements 461 are the upper limit value or less and the lower limit value or more) is modulated as the ON drive voltage used for image recording The calibration is completed (step S20).

  As described above, in the image recording apparatus 1, each light is adjusted so that the light quantity distribution acquired by the light receiving unit 34 approximates the target light quantity distribution while all the light modulation elements 461 in the light modulation element array 460 are turned on. The drive voltage to the modulation element 461 is corrected, and thereby the distribution of the output light quantity from the spatial light modulator 46 is corrected. In the first process of step S18, the drive voltage for each light modulation element 461 may be a value obtained by increasing or decreasing the initial drive voltage according to the correction coefficient, and the number of repetitions of the processes of steps S18 and S19 may be reduced. .

  In the image recording apparatus 1, once the target light amount distribution of the all-ON lighting pattern is acquired, in the second and subsequent calibrations, in principle, only the processing in steps S18 to S20 is performed, and spatial light modulation is performed. The distribution of the output light quantity from the device 46 is corrected according to the target light quantity distribution. In addition, when the setting state of the image recording apparatus 1 has changed greatly by replacing various parts related to light emission, or when a long time has elapsed since the last acquisition of the target light amount distribution, etc. The processing of steps S11 to S17 is performed again to re-acquire the target light amount distribution of the all-ON lighting pattern.

  By the way, when assuming the calibration of the comparative example in which the ON drive voltage having a constant value in the light amount distribution of the all ON lighting patterns is assumed, the line width of the pattern when actually recording an image on the substrate 9 is considered. Therefore, the line width of the pattern in the image recorded on the substrate 9 cannot always be adjusted with high accuracy. In addition, it is conceivable to acquire the light amount distribution with the ON / OFF lighting pattern and adjust the drive voltage so that the width of the portion corresponding to each ON element group is within a certain range. In the calibration, it is necessary to obtain the width of the portion corresponding to each ON element group in the light amount distribution of the ON / OFF lighting pattern. In practice, a large number of light modulation elements 461 are arranged in the spatial light modulator 46. Therefore, it takes a long time for each calibration.

  On the other hand, in the image recording apparatus 1 in FIG. 1, the ON element group 462 and the OFF element group 463 are alternately set in the arrangement direction in the light modulation element array 460, and the light quantity distribution of the ON / OFF lighting pattern is acquired. In a part corresponding to each ON element group 462 in the light quantity distribution of the ON / OFF lighting pattern, a light quantity parameter value indicating a width equal to or larger than a predetermined light quantity is obtained, and fluctuations in the X direction of the light quantity parameter values in all the ON element groups 462 are obtained. A fluctuation trend curve indicating the trend is acquired. Then, by creating the target light quantity distribution of the all-ON lighting pattern based on the fluctuation tendency curve, after creating the target light quantity distribution once, all the light modulation elements 461 in the light modulation element array 460 can be easily turned on. In the light modulation element array 460, when the ON element group 462 and the OFF element group 463 are repeated in the arrangement direction, the width corresponding to the ON element group 462 is almost equal to or larger than the predetermined light quantity. As a result, it is possible to adjust the line width of the pattern in the image recorded on the substrate 9 with high accuracy.

  In the image recording apparatus 1, the number of the light modulation elements 461 in the ON element group 462 and the number of the light modulation elements 461 in the OFF element group 463 are applied to the substrate 9 when acquiring the light amount distribution of the ON / OFF lighting pattern. 1 or more corresponding to the minimum line width capable of stable drawing (5 or more in the image recording apparatus 1 in FIG. 1, but 3 or more depending on the design of the projection optical system), and preferably the minimum line width. The corresponding number is 5 times or less. As a result, it is possible to obtain a preferable target light amount distribution in consideration of the minimum line width in actual image recording.

  Furthermore, when the calculation unit 62 acquires the fluctuation trend curve, the calculation of the fluctuation parameter value in all the ON element groups 462 is performed to reduce the fluctuation of the light amount parameter value, so that the actually obtained fluctuation trend curve is substantially reduced. To be smoothed. Here, the value of the light quantity parameter in all the ON element groups 462 usually varies gently, but even if an abnormal value of the light quantity parameter is acquired due to the influence of noise or the like, the value of the light quantity parameter As a result of the calculation for reducing the fluctuation, it is possible to obtain a preferable fluctuation tendency curve while suppressing the influence of the abnormal value, and appropriately calibrate the spatial light modulator 46. The fluctuation trend curve may be smoothed by removing high-frequency components using FFT (Finite Fourier transform) or the like.

  In the above description, the width W1 of the portion that is equal to or larger than the light amount threshold value T1 in each ON light amount portion 71 in FIG. 7 is obtained as the light amount parameter, but depending on the type of the object on which the image is recorded, the steps S15 and S16 In the processing, the accumulated light amount is accumulated by the maximum light amount of each ON light amount portion 71 (indicated by reference numeral H1 in FIG. 7) or the width of the portion that is equal to or larger than the predetermined light amount in each ON light amount portion 71. The amount of light (a value corresponding to the area of the region A1 with a parallel diagonal line in FIG. 7) is used as a light amount parameter, and a fluctuation tendency curve indicating the variation tendency in the X direction of the light amount parameter value in all the ON element groups 462 is acquired. May be. In any case, the other processes (steps S11 to S14 and S17 to S20) are the same as the above case, and thus, all the light modulation elements 461 in the light modulation element array 460 are easily turned on and calibrated. The light quantity parameter value of the portion corresponding to the ON element group 462 in the light quantity distribution when the ON element group 462 and the OFF element group 463 are repeated in the arrangement direction in the light modulation element array 460 is made substantially constant. be able to.

  Next, an example in which the target light quantity distribution of the all-ON lighting pattern is obtained while omitting the processes of steps S12 and S13 in the process related to calibration in FIG.

  First, in the image recording apparatus 1, a constant drive voltage is input as an initial drive voltage to the drive circuits 611 of all the light modulation elements 461 in the spatial light modulator 46, so that all the light modulation elements 461 are turned on. Thus, the light amount distribution of the all-ON lighting pattern shown in FIG. 11 is acquired (step S11). When the driving voltages for all the light modulation elements 461 are constant, the light amount distribution value of the all-ON lighting pattern is not usually constant due to manufacturing variations of the light modulation elements 461 and the like. In the following description, the light amount distribution acquired in the process of step S11 is referred to as an uncorrected initial light amount distribution.

  Subsequently, in the light modulation element array 460, the ON element group 462 and the OFF element group 463 are alternately set in the arrangement direction. At this time, the initial drive voltage when the uncorrected initial light amount distribution shown in FIG. 11 is acquired is input to the drive circuit 611 of each light modulation element 461 in the ON element group 462. The light receiving unit 34 receives the light from the light modulation element array 460, thereby acquiring the light amount distribution of the ON / OFF lighting pattern (see FIG. 7) (step S14).

  Here, the difference between the light amount distribution of the ON / OFF lighting pattern acquired in this processing example and the light amount distribution of the ON / OFF lighting pattern acquired in the above processing example in which the processing in steps S12 and S13 is performed. Is described. As described above, in the above processing example in which the processing of steps S12 and S13 is performed, the acquisition of the light amount distribution of all ON lighting patterns until the measurement values corresponding to all the light modulation elements 461 become substantially constant, and Since the value of the initial drive voltage is changed, in the light quantity distribution of the ON / OFF lighting pattern, the same drive voltage as that in the ON / OFF lighting pattern is used for the light modulation elements 461 included in the ON element group 462. It is assumed that the light quantity distribution value is constant when the all-ON lighting pattern is used. On the other hand, in the present processing example, the processing in steps S12 and S13 is omitted, so that the light amount distribution of the ON / OFF lighting pattern acquired in the processing in step S14 includes the light included in the ON element group 462. It is considered that the influence of variation in the light amount distribution (uncorrected initial light amount distribution) when the modulation element 461 is set to the all-ON lighting pattern using the same drive voltage as the ON / OFF lighting pattern is included. Can do.

  When the light quantity distribution of the ON / OFF lighting pattern is acquired, the calculation unit 62 has a width that is greater than or equal to a predetermined light quantity and a maximum light quantity in the ON light quantity portion 71 corresponding to each ON element group 462 in the light quantity distribution of the ON / OFF lighting pattern. Alternatively, the value of the light quantity parameter indicating the accumulated light quantity obtained by integrating the light quantity with a width equal to or greater than the predetermined light quantity is obtained, and thereafter, the fluctuation of the light quantity parameter value is reduced by calculation (step S15). Then, a fluctuation tendency curve indicating the fluctuation tendency in the X direction of the light amount parameter values in all the ON element groups 462 is acquired as shown in FIG. 12 (step S16). In FIG. 12, the fluctuation trend curve acquired in the present processing example is indicated by a solid line denoted by reference numeral 721, and the fluctuation trend curve acquired in the above processing example in which the processes of steps S12 and S13 are performed are denoted by reference numerals. This is indicated by a broken line 722.

  As described above, the light quantity distribution of the ON / OFF lighting pattern acquired in the process of step S14 includes the influence of the variation in the value of the uncorrected initial light quantity distribution shown in FIG. Then, the target light amount distribution of the all-ON lighting pattern is created in consideration of the variation in the value of the uncorrected initial light amount distribution. That is, the larger the value obtained by dividing the value of the fluctuation tendency curve at the position on the projection plane corresponding to each light modulation element 461 by the value of the uncorrected initial light amount distribution at that position, the smaller the value. The uncorrected initial light amount distribution is corrected, and as shown in FIG. 13, the target light amount distribution of the all-ON lighting pattern is created (step S17).

  When the target light amount distribution of the all-ON lighting pattern is created, the image recording apparatus 1 sets all the light modulation elements 461 in the light modulation element row 460 in the same manner as in the above processing example in which the processes in steps S12 and S13 are performed. While being in the ON state, the drive voltage to each of the light modulation elements 461 is corrected and the ON drive voltage is acquired so that the light amount distribution acquired by the light receiving unit 34 approximates the target light amount distribution. The distribution of the amount of light output from the modulator 46 is corrected (steps S18 to S20).

  As described above, the target light amount distribution of the all-ON lighting pattern can be created by omitting the processes in steps S12 and S13. However, in order to make the value of the light quantity parameter corresponding to the ON element group 462 in the light quantity distribution when the ON element group 462 and the OFF element group 463 are repeated in the arrangement direction in the light modulation element row 460 with high accuracy, is constant. By performing the processes of steps S12 and S13 to obtain a corrected initial light amount distribution whose value is substantially constant, variation in the value of the light amount distribution to be corrected is created when creating the target light amount distribution of the all-ON lighting pattern. It is preferable that the influence of is excluded.

  FIG. 14 is a diagram showing a configuration of an image recording apparatus 1a according to the second embodiment of the present invention. The image recording apparatus 1a includes one optical head 41a that emits light for image recording and a holding drum 70 that is a holding unit that holds a recording medium 9a on which an image is recorded on an outer surface. An image is recorded on the recording medium 9a by drawing by light irradiation (exposure) by the optical head 41a. As the recording medium 9a, for example, a printing plate, a film for forming a printing plate, or the like is used. Note that a photosensitive drum for plateless printing may be used as the holding drum 70. In this case, the recording medium 9a corresponds to the surface of the photosensitive drum, and the holding drum 70 integrally holds the recording medium 9a. Can be considered.

  The holding drum 70 is rotated around the central axis of the cylindrical surface by the motor 81, whereby the optical head 41a irradiates the recording medium 9a in the main scanning direction (light from a plurality of light modulation elements described later). It moves at a relatively constant speed (in a direction perpendicular to the direction in which the positions are arranged). The optical head 41a can be moved in the sub-scanning direction (perpendicular to the main scanning direction) parallel to the rotation axis of the holding drum 70 by the motor 82 and the ball screw 83, and the position of the optical head 41a is detected by the encoder 84. The As described above, the moving mechanism including the motors 81 and 82 and the ball screw 83 causes the outer surface of the holding drum 70 and the recording medium 9a to move in the main scanning direction at a constant speed with respect to the optical head 41a having the spatial light modulator. It relatively moves and also moves relatively in the sub-scanning direction intersecting the main scanning direction. The motors 81 and 82 and the encoder are connected to the control unit 6a, and the control unit 6a controls the emission of the signal light from the spatial light modulators in the motors 81 and 82 and the optical head 41a, thereby recording on the holding drum 70. Image recording by light is performed on the medium 9a.

  A light receiving unit 34 for detecting light from each light modulation element of the spatial light modulator in the optical head 41 a is disposed on the side of the holding drum 70, and the optical head 41 a is received by the motor 82 and the ball screw 83. It is possible to move to a position that passes through. The output from the light receiving unit 34 is input to the calculation unit 62 of the control unit 6a.

  FIG. 15 is a diagram showing an outline of the internal configuration of the optical head 41a. In the optical head 41a, a light source 43a, which is a bar-type semiconductor laser having a plurality of light emitting points in a row, and a spatial light modulator 46 having a diffraction grating type light modulation element array are arranged. The light is guided to the spatial light modulator 46 through a lens 471 (actually constituted by a condensing lens, a cylindrical lens, etc.) and a prism 472. At this time, the light from the light source 43a is converted into linear light (light having a linear cross section) and is irradiated onto a plurality of light modulation elements arranged in a line.

  Each light modulation element of the spatial light modulator 46 is controlled by a modulator control unit 61 (see FIG. 14) of the control unit 6a. In FIG. 15, the plurality of drive circuits 611 of the modulator control unit 61 are shown as one block. The zero-order light emitted from the light modulation element is returned to the prism 472, and the first-order diffracted light is guided in a direction different from that of the prism 472. In order to prevent stray light from being generated, the first-order diffracted light is shielded by a light shielding unit (not shown).

  The zero-order light from each light modulation element is reflected by the prism 472 and guided to the recording medium 9a outside the optical head 41a via the zoom lens 473 so that the images of the plurality of light modulation elements are arranged in the sub-scanning direction. Formed on the recording medium 9a. The magnification of the zoom lens 473 is variable by a zoom lens drive motor 474, whereby the resolution of the recorded image is changed.

  In the processing relating to the calibration of the spatial light modulator 46 in the image recording apparatus 1a of FIG. 14, the optical head 41a moves to a position facing the light receiving unit 34 as indicated by a two-dot chain line in FIG. Thus, the light from the spatial light modulator 46 is received. And the target light quantity distribution of the all ON lighting pattern based on a fluctuation tendency curve is acquired similarly to the said 1st Embodiment. As a result, in the image recording apparatus 1a, the ON element group and the OFF element group are repeated in the arrangement direction in the light modulation element array while performing easy calibration with all the light modulation elements in the light modulation element array being in the ON state. In this case, the value of the light quantity parameter of the portion corresponding to the ON element group in the light quantity distribution can be made substantially constant, and as a result, it is possible to record an image on the recording medium 9a with high accuracy.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible.

  As described above, in the above processing example in which the processing of steps S12 and S13 in FIG. 5 is performed, the ON / OFF lighting pattern light amount distribution is ON / OFF with respect to the light modulation elements 461 included in the ON element group 462. Since it is assumed that the value of the light intensity distribution is constant when the all-ON lighting pattern is set using the same drive voltage as in the OFF lighting pattern, the light quantity to be corrected when creating the target light intensity distribution of the all ON lighting pattern Although the influence of the variation in the value in the distribution (corrected initial light amount distribution) is not taken into consideration, the target light amount distribution is actually created in the process of step S17 also in the above processing example in which the processes of steps S12 and S13 are performed. In this case, the value of the fluctuation tendency curve at the position on the projection plane corresponding to each light modulation element 461 is divided by the value of the corrected initial light amount distribution at the position. It can be regarded as correction coefficient to be a smaller value the larger the value is required.

  Further, when creating the target light amount distribution of the all-ON lighting pattern, the value of the variation tendency curve at the position on the projection surface corresponding to each light modulation element 461 is used as the initial light amount distribution (correction) of the all-ON lighting pattern at that position. If the initial light intensity distribution is corrected so that the smaller the value divided by the value of the (initial initial light intensity distribution or uncorrected initial light intensity distribution), the smaller the value, the correction coefficient need not necessarily be obtained. The target light amount distribution may be acquired by various methods.

  In the image recording apparatuses 1 and 1a, the signal light for drawing does not necessarily have to be zero-order light, and the first-order diffracted light may be signal light. Further, if the flexible ribbon 461a and the fixed ribbon 461b extending in the direction perpendicular to the arrangement direction can be regarded as a belt-like reflecting surface, it is not necessary to have a ribbon shape in a strict sense. For example, the block-shaped upper surface may serve as a reflecting surface of the fixed ribbon.

  In the above calibration-related processing for creating the target light amount distribution of all ON lighting patterns based on the fluctuation tendency curve, it is possible to easily suppress variations in light amount parameter values depending on the diffraction grating type spatial light modulator. However, the spatial light modulator is not limited to the diffraction grating type, and may be a liquid crystal shutter (liquid crystal array), for example. Furthermore, the light modulation elements 461 are not limited to those that reflect light, and for example, a laser array may serve as the light modulation element array 460. Even in these cases, appropriate image recording can be realized by adopting the processing related to the calibration.

  In addition, a two-dimensional spatial light modulator (for example, a micromirror array) may be employed. In this case, calibration for the light modulation element array in the above embodiment is performed for each one-dimensional array of light modulation elements. Is performed.

  In the image recording on the substrate 9 (or the recording medium 9a), if the substrate 9 moves in the direction intersecting the X direction corresponding to the arrangement direction of the light modulation elements 461 on the projection surface, the moving direction of the substrate 9 Need not be perpendicular to the X direction. In the image recording apparatus 1, the optical head 41 moves in the main scanning direction without moving the substrate 9, so that the substrate 9 moves relative to the optical head 41 in the main scanning direction on the projection surface. May be.

  The object on which the image is recorded may be a material coated with a photosensitive material such as a printed wiring board or a semiconductor substrate, or another material having photosensitivity, and is a material that reacts to heat due to light irradiation. There may be. In addition, the calibration-related processing for creating the target light amount distribution of the all-ON lighting pattern based on the fluctuation tendency curve may be used for applications other than image recording. In this case, each ON in the ON / OFF lighting pattern The number of light modulation elements 461 included in the element group and the OFF element group may be one or more.

1 is a side view of an image recording apparatus according to a first embodiment. It is a top view of an image recording device. It is a figure which shows a spatial light modulator. It is a figure which shows the cross section of a light modulation element row | line | column. It is a figure which shows the cross section of a light modulation element row | line | column. It is a figure which shows the flow of the process which concerns on the calibration of a spatial light modulator. It is a figure which shows the corrected initial stage light quantity distribution. It is a figure which shows light quantity distribution of an ON / OFF lighting pattern. It is a figure which shows a fluctuation tendency curve. It is a figure which shows a correction coefficient. It is a figure which shows the target light quantity distribution of all the ON lighting patterns. It is a figure which shows uncorrected initial light quantity distribution. It is a figure which shows a fluctuation tendency curve. It is a figure which shows the target light quantity distribution of all the ON lighting patterns. It is a figure which shows the structure of the image recording device which concerns on 2nd Embodiment. It is a figure which shows the internal structure of an optical head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Substrate 9a Recording medium 34 Light-receiving part 46 Spatial light modulator 71 ON light quantity part 91 Upper surface 460 Light modulation element row | line | column 461 Light modulation element 462 ON element group 463 OFF element group S11-S20 Step W1 Width

Claims (5)

In a spatial light modulator having a light modulation element array in which a large number of light modulation elements are arranged in a predetermined arrangement direction, the input value to each light modulation element of the light modulation element array is corrected to correct the input value from the spatial light modulator. A spatial light modulator calibration method for correcting the distribution of the output light quantity of
a) All the light modulation elements in the light modulation element array are in an ON state in which irradiated light is guided to a predetermined projection surface, and the light modulation element array is received by a light receiving unit disposed on the projection surface. Receiving a light from a first light amount distribution in a direction corresponding to the arrangement direction on the projection plane;
b) ON element groups in which a predetermined number of light modulation elements continuous in the arrangement direction are turned on using the input values to the light modulation elements in the step a), and a predetermined number of continuous light elements in the arrangement direction The light receiving unit receives light from the light modulation element array in the arrangement direction while repeatedly setting the OFF element group in which the light modulation elements are in the OFF state, and corresponds to the arrangement direction on the projection plane. Obtaining a second light amount distribution in a direction to perform,
c) In a portion corresponding to each ON element group in the second light amount distribution, a light amount parameter value indicating a width equal to or greater than a predetermined light amount, a maximum light amount, or an accumulated light amount obtained by integrating the light amount by the width is obtained, and all ON elements are obtained. Obtaining a fluctuation tendency curve indicating a fluctuation tendency in a direction corresponding to the arrangement direction of the light amount parameter values in the group;
d) The value obtained by dividing the value of the fluctuation tendency curve at the position on the projection surface corresponding to each light modulation element by the value of the first light quantity distribution at the position is set to be smaller as the value is larger. Correcting the first light quantity distribution to create a target light quantity distribution;
e) The input values to the respective light modulation elements are set so that the light quantity distribution acquired by the light receiving unit approximates the target light quantity distribution while all the light modulation elements in the light modulation element row are turned on. A process of correcting,
A spatial light modulator calibration method comprising: The spatial light modulator calibration method according to claim 1,
The method of calibrating a spatial light modulator, wherein in the step a), the first light quantity distribution is set to a constant value. A method for calibrating a spatial light modulator according to claim 1 or 2,
An image is recorded on the object by moving the object relative to the spatial light modulator in a direction crossing a direction corresponding to the arrangement direction on the projection plane,
The number of light modulation elements in the ON element group and the number of light modulation elements in the OFF element group are equal to or greater than the number corresponding to the minimum line width that can be drawn on the object. Calibration method. A method for calibrating a spatial light modulator according to any one of claims 1 to 3,
The method of calibrating a spatial light modulator, wherein the step c) includes a step of reducing the fluctuation of the value after obtaining the value of the light quantity parameter in all the ON element groups. A method for calibrating a spatial light modulator according to any one of claims 1 to 4,
A spatial light modulator calibration method, wherein the light modulation element array is a diffraction grating type light modulation element array in which strip-shaped fixed reflection surfaces and flexible reflection surfaces are alternately arranged.

Images